This invention relates to an electronic musical instrument of the type in which a musical tone signal is formed by executing computations according to a mathematical formula such as a frequency modulation formula.
Conventional electronic musical instruments using computations of a frequency modulation formula or the like for obtaining a musical tone signal have on one hand advantages and on the other hand disadvantages over known electronic musical instrument in which the tone coloring is determined such as by filters or by tone wave memory reading. One of the advantages is that a musical tone signal rich in tone colors can be generated in such conventional electronic musical instruments. However, the disadvantages also exist in that a rather complicated computation device with capabilities of high speed computational processing is required when a complicated computation for a muscial tone signal is necessary or when a plurality of musical tone signals are formed simultaneously with one another.